[R-sig-Geo] reboxing, or 3D interpolation?

[Tom Roche]

Having done "regridding" (aka 2D interpolation), I'd like to know
how to do "reboxing" (aka 3D interpolation) in R. Can anyone point me
to docs explaining how to do this, or example code that does this?
What I mean, why I ask:

I'm a student attempting to incorporate N2O emissions inventories
(EIs), initial conditions (ICs), and boundary conditions (BCs) from
relatively coarse-scaled global inventories (with horizontal grids on
the order of degrees lon-lat) into a relatively fine-scaled regional
atmospheric model (12-km LCC horizontal). The emissions are all from
surface, hence effectively 2D, and I now know how to "regrid," or
interpolate from one 2D grid to another.

However the model and the N2O IC/BCs are 3D: the cells are boxes,
not just grids. And of course the model (on the one hand) and the
N2O IC/BCs have different vertical layering (i.e., numbers of layers,
and top height, or maximum vertical extent), as well as different
horizontal grids. I'd like to know: is there R code available that
will "rebox," i.e., interpolate vertically as well as horizontally?

thanks in advance, and feel free to forward, Tom Roche <Tom_Roche at pobox.com>